Modified Vaccinia Ankara (MVA) virus is related to vaccinia virus, a member of the genera Orthopoxvirus, in the family of Poxyiridae. MVA was generated by 516 serial passages on chicken embryo fibroblasts of the Ankara strain of vaccinia virus (CVA) (for review see Mayr, A., et al. Infection 3, 6-14 (1975)). As a consequence of these long-term passages, the genome of the resulting MVA virus had about 31 kilobases of its genomic sequence deleted and, therefore, was described as highly host cell restricted for replication to avian cells (Meyer, H. et al., J. Gen. Virol. 72, 1031-1038 (1991)). It was shown in a variety of animal models that the resulting MVA was significantly avirulent (Mayr, A. & Danner, K., Dev. Biol. Stand. 41: 225-34 (1978)). Additionally, this MVA strain has been tested in clinical trials as a vaccine to immunize against the human smallpox disease (Mayr et al., Zbl. Bakt. Hyg. I, Abt. Org. B 167, 375-390 (1987); Stickl et al., Dtsch. med. Wschr. 99, 2386-2392 (1974)). These studies involved over 120,000 humans, including high-risk patients, and proved that, compared to vaccinia-based vaccines, MVA had diminished virulence or infectiousness, while it induced a good specific immune response.
In the following decades, MVA was engineered for use as a viral vector for recombinant gene expression or as a recombinant vaccine (Sutter, G. et al., Vaccine 12: 1032-40 (1994)).
Even though Mayr et al. demonstrated during the 1970s that MVA is highly attenuated and avirulent in humans and mammals, certain investigators have reported that MVA is not fully attenuated in mammalian and human cell lines since residual replication might occur in these cells. (Blanchard et al., J Gen Virol 79, 1159-1167 (1998); Carroll & Moss, Virology 238, 198-211 (1997); Altenberger, U.S. Pat. No. 5,185,146; Ambrosini et al., J Neurosci Res 55 (5), 569 (1999)). It is assumed that the results reported in these publications have been obtained with various known strains of MVA, since the viruses used essentially differ in their properties, particularly in their growth behavior in various cell lines. Such residual replication is undesirable for various reasons, including safety concerns in connection with use in humans.
Strains of MVA having enhanced safety profiles for the development of safer products, such as vaccines or pharmaceuticals, have been described. See U.S. Pat. Nos. 6,761,893 and 6,193,752. Such strains are capable of reproductive replication in non-human cells and cell lines, especially in chicken embryo fibroblasts (CEF), but are not capable of significant reproductive replication in certain human cell lines known to permit replication with known vaccinia strains. Such cell lines include a human keratinocyte cell line, HaCat (Boukamp et al. J Cell Biol 106 (3): 761-71 (1988)), a human cervix adenocarcinoma cell line, HeLa (ATCC No. CCL-2), a human embryo kidney cell line, 293 (ECACC No. 85120602), and a human bone osteosarcoma cell line, 143B (ECACC No. 91112502). Such strains are also not capable of significant reproductive replication in vivo, for example, in certain mouse strains, such as the transgenic mouse model AGR 129, which is severely immune-compromised and highly susceptible to a replicating virus. See U.S. Pat. Nos. 6,761,893. One such MVA strain and its derivatives and recombinants, referred to as “MVA-BN,” have been described. See U.S. Pat. Nos. 6,761,893 and 6,193,752.
MVA and MVA-BN have each been engineered for use as a viral vector for recombinant gene expression or as a recombinant vaccine. See, e.g., Sutter, G. et al., Vaccine 12: 1032-40 (1994), U.S. Pat. Nos. 6,761,893 and 6,193,752.
Certain approaches to cancer immunotherapy have included vaccination with tumor-associated antigens. In certain instances, such approaches have included use of a delivery system to promote host immune responses to tumor-associated antigens. In certain instances, such delivery systems have included recombinant viral vectors. See, e.g., Harrop et al., Front. Biosci. 11:804-817 (2006); Arlen et al., Semin. Oncol. 32:549-555 (2005); Liu et al., Proc. Natl. Acad. Sci. USA 101 (suppl. 2):14567-14571 (2004).
HER-2 is a tumor-associated antigen that is over-expressed in tumor cells of a number of cancer patients. Immunization with various HER-2 polypeptides has been used to generate an immune response against tumor cells expressing this antigen. See, e.g., Renard et al., J. Immunology 171:1588-1595 (2003); Mittendorf et al., Cancer 106:2309-2317 (2006).
Taxanes, such as paclitaxel and docetaxel, have been used as chemotherapies for cancer patients. Chemotherapy with taxanes has been combined with different tumor vaccine treatments, resulting in a variety of results. See, Chu et al., J. Immunotherapy 29: 367-380 (2006); Machiels et al., Cancer Res. 61: 3689-3697 (2001); Prell et al., Cancer Immunol. Immunother. 55: 1285-1293 (2006); Arlen et al., Clinical Breast Cancer 7: 176-179 (2006); and Arlen et al., Clinical Cancer Res. 12: 1260-1269 (2006). The combination of cancer vaccines with chemotherapies has been reviewed in Chong et al., Expert Opin. Phamacother. 6: 1-8 (2005) and Emens et al., Endocrine-Related Cancer 12: 1-17 (2005).
Based on the above, a need in the art exists for reagents and methods for cancer therapy.